cameo: added command "append", improved file output error checking

- README: added description of "append"
- lang.l, lang.y: added command "append"
- gnuplot.h, gnuplot.c (gnuplot_append): append gnuplot paths to an
  existing file
- gnuplot.c (gnuplot_do_write): if writing to standard output, at least
  check that fflush() works at the end

cameo/README

@@ -45,10 +45,13 @@ translation.
 File output:
 
   write [<filename>]
+  append [<filenname>]
 
 Writes all loaded paths in gnuplot format to the specified file. If the
 file name is omitted, "write" writes to standard output.
 
+"append" is like "write", except that it appends to an existing file.
+
 File names can contain spaces and any printable characters, but no leading
 or trailing spaces. It is not possible to place a comment after a file
 name or at a place where a file name could be.

cameo/gnuplot.c

@@ -14,6 +14,7 @@
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include <sys/stat.h>
 
 #include "path.h"
 #include "gnuplot.h"
@@ -99,8 +100,13 @@ static int gnuplot_do_write(FILE *file, const struct path *paths)
 			if (fprintf(file, "%f %f %f\n", p->x, p->y, p->z) < 0)
 				return 0;
 	}
-	if (file != stdout && fclose(file) < 0)
-		return 0;
+	if (file == stdout) {
+		if (fflush(file) == EOF)
+			return 0;
+	} else {
+		if (fclose(file) < 0)
+			return 0;
+	}
 	return 1;
 }
 
@@ -120,3 +126,30 @@ void gnuplot_write(const char *name, const struct path *paths)
 	}
 }
 
+
+void gnuplot_append(const char *name, const struct path *paths)
+{
+	FILE *file;
+	struct stat st;
+
+	if (!name) {
+		printf("\n");
+		gnuplot_write(NULL, paths);
+		return;
+	}
+	file = fopen(name, "a");
+	if (!file) {
+		perror(name);
+		exit(1);
+	}
+	if (stat(name, &st) < 0) {
+		perror("lstat");
+		exit(1);
+	}
+	if (!S_ISREG(st.st_mode) || st.st_size)
+		fprintf(file, "\n");
+	if (!gnuplot_do_write(file, paths)) {
+		perror(name);
+		exit(1);
+	}
+}

cameo/lang.l

@@ -51,6 +51,8 @@ NUM	-?[0-9]+\.?[0-9]*
 <INITIAL>translate		return TOK_TRANSLATE;
 <INITIAL>z			return TOK_Z;
 
+<INITIAL>append			{ BEGIN(FILENAME);
+				  return TOK_APPEND; }
 <INITIAL>gerber			{ file_name_follows = 1;
 				  return TOK_GERBER; }
 <INITIAL>gnuplot		{ file_name_follows = 1;

cameo/lang.y

@@ -152,7 +152,7 @@ static struct path **classify(struct path **anchor, struct path *path)
 %token		TOK_ALIGN TOK_ARRAY TOK_CLEAR TOK_DRILL TOK_EMPTY
 %token		TOK_MILL TOK_OFFSET TOK_REMAINDER TOK_RESET
 %token		TOK_TRANSLATE TOK_Z
-%token		TOK_GERBER TOK_GNUPLOT TOK_EXCELLON TOK_WRITE
+%token		TOK_APPEND TOK_GERBER TOK_GNUPLOT TOK_EXCELLON TOK_WRITE
 %token		TOK_DOG TOK_INSIDE
 
 %token	<num>	NUM_EXP_MIL NUM_EXP_MM NUM_IMP_MIL NUM_IMP_MM REF
@@ -241,6 +241,12 @@ command:
 			gnuplot_write($2, paths);
 			translate(0, 0, -zo);
 		}
+	| TOK_APPEND opt_filename
+		{
+			translate(0, 0, zo);
+			gnuplot_append($2, paths);
+			translate(0, 0, -zo);
+		}
 	| TOK_DRILL dimen dimen
 		{
 			struct path **walk;